Studies on polyester-poly(ethyl acrylate-co-styrene) interpenetrating polymer networks

Polyester-poly(ethyl acrylate-co-styrene) interpenetrating polymer networks (IPNs) were prepared by the two step in situ sequential technique. Both semi- and full IPNs were synthesized. Poly(ethyl acrylate-co-styrene) acts as the rubbery phase and polyester as the hard, brittle phase. It was found that with increasing proportion of ethyl acrylate in the IPN, elongation at break (EB), toughness and molecular weight between cross-links (Mc) are higher but tensile strength (TS), modulus, tear strength and density becomes lower. Full IPNs, where both networks are cross-linked, have higher TS, modulus, tear strength, density and hardness but lower EB toughness. Scanning electron microscopy revealed that domain size is primarily dependent on the ethyl acrylate content of the blend and also on the amount of cross-linker. Evidence for cross-linking of unsaturated polyester through styrene bridges in the IPNs was obtained.